Process for making a container with a pressure equalization opening and containers produced accordingly

ABSTRACT

A process for the production of a container ( 1 ) comprising an outer container ( 2 ), an inner bag ( 3 ) disposed therein and a pressure equalisation opening ( 10 ) disposed in the outer container ( 2 ), and also a container ( 1 ) produced according to this process, is described, wherein firstly a pre-moulding, comprising two coaxial tubes, is first produced by co-extrusion with the help of a blow mould and with an outwardly-projecting base seam ( 5 ) being formed. The process is to form a pressure equalisation opening ( 10 ) in the outer container ( 2 ) of the container ( 1 ) without endangering the integrity of the container ( 1 ), wherein a lower wastage rate and higher productivity are to be achieved. This is attained by a process wherein the base seam ( 5 ) is partially cut off and a force which acts in the direction of the seam is introduced into the pre-moulding, which still has a temperature of 40° C. to 70°C., which force breaks open and plastically deforms the base seam ( 5 ) so that a pressure equalisation opening ( 10 ) is formed in the base area ( 4 ).

RELATED APPLICATIONS

Benefit under 35 U.S.C. §119(e) of prior U.S. provisional applicationSerial No. 60/220,835, filed Jul. 26, 2000, is hereby claimed.

The invention relates to a process for the production of a containerprovided with a container opening, having a substantially rigid outercontainer and an inner bag disposed therein which is in contact with thelater container contents, these respectively comprising differentthermoplastic plastics which are not bonded to each other, and apressure equalisation opening, disposed in the outer container, whichequalises a pressure difference between the outer container and theinner bag, wherein a preliminary moulding, comprising two coaxial tubeswhich have a sufficient length for manufacture of the container, isfirst produced by co-extrusion between the opened halves of the blowmould, the blow mould is closed and with that an outwardly-projectingbase seam is formed, the excess material in the base area of thecontainer that is to be manufactured being squashed out in such a waythat the material of the outer container which is in contact in the areaof the seam is welded together, the tube which forms the inner bag isclamped, axially fixed and welded between the wall sections of the outercontainer and the inner bag is subjected to pressure, so that the wallsof the preliminary moulding lie against the contours of the blow mouldfrom inside.

Furthermore, the invention relates to a container, preferably producedaccording to the process, with a container opening, substantiallycomprising a rigid outer container and an inner bag disposed therein,which is in contact with the later container contents.

A process of the type considered here is disclosed in WO 99/11451. Thecharacterising feature of this process is that the pressure equalisationopening, via which the pressure difference existing between the outercontainer and the inner bag is equalised, is preferably configured as alenticular or ellipsoid hole in the outer container, wherein this holecomes into being after completion of the actual forming process bycutting away a wall section of the outer container with the help of acutting tool.

This means that the outer wall, against which the very thin flexibleinner bag lies, must be completely cut away in at least one very smallarea without causing any damage to the inner bag. Processing of theouter container implies an indispensable contact between the cuttingtool and the inner bag. The substantially most important qualityfeatures of the process and of the container manufactured according tothe process cannot be realised simultaneously to an equal degree. Theydiverge in the present process, or container. On the one hand it must bepossible to effect pressure equalisation between the outer container andthe inner bag, which is necessary due to the volume reduction in theinner bag associated with the dispensing of the container contents. Onthe other hand, the container must be completely sealed, i.e. damage tothe inner bag must be avoided at all costs, otherwise the containerwould be unusable. The difficulty of fulfilling both taskssatisfactorily is discussed in WO 99/11451. For example, it is statedthat due to the wall strength tolerances of the outer container whichoccur as a result of its fabrication, wherein the wall thickness canvary between 1 and 1.5 mm, in practice the depth of cut must be set sothat it is guaranteed that a hole which actually penetrates the outercontainer results from the cutting process. Damage to the inner bagcannot be ruled out in every case. For this reason, preferred processsteps and tools which are to be used in order to minimise the danger ofdamage to the inner bag are described in WO 99/11451.

A further disadvantage of the disclosed process is that theconfiguration of the pressure equalisation opening does not take placeimmediately after the forming process. The process step of cuttingcannot take place on the plastic blowing machine, and especially notwhen the blowing mould is closed. The additional processing machine, orits tools, which are required for the suggested cutting process and theworking steps which have been made necessary lead to an increase incosts and a reduction in productivity.

Furthermore, it can be desirable to connect a pump or an atomiser to thecontainer opening of the container of the considered type, via which thematerial in the inner bag of the container is charged or removed.Depending on the configuration of the utilised pump or atomiser, thepressure equalisation opening can be partially or completely closed bythe suitable pump or atomiser. In other words, it is not possible toattach any adaptor to the container in question, rather the particularposition of the pressure equalisation opening of the respectiveembodiment example must be taken into consideration. Especiallyunfavourable positions for the wall opening are, in this case, positionsin the shoulder area and in the area of the container jacket surface.The most suitable position for the wall opening, the container base, isexpressly not mentioned.

On this basis, the object of the invention at issue is to introduce aprocess via which a pressure equalisation opening disposed in the outercontainer of a container of the type in question can be configuredwithout endangering the integrity of the container, wherein the processshould only have a minimum of process steps and should cost less thanthe process utilised according to the prior art whilst at the same timeallowing a lower wastage rate and higher productivity.

Furthermore, a container should be introduced which has a pressureequalisation opening in its outer container without its inner bag beingdamaged during cutting of this opening, and which has no otherdisadvantages.

The process object is solved by the process according to the invention,where on closing the blow mould and hence forming the base seam, theseam of the inner bag is at least partially fixed axially in the seam ofthe outer container and at least one pressure equalisation opening isformed in that the base seam is at least partially but preferably notcompletely cut off after shaping, so that at least a partial area of theseam of the inner bag remains fixed in the seam of the outer container,and following this a radial force, acting in the direction of the seam,is introduced into the base area in such a way that the base seam breaksup, wherein the temperature of the pre-moulding is between 40° C. and70° C. on cutting off the base seam and the outer container is stillplastically deform able to some degree so that a permanent deformationresults from the force which is not neutralised by elastic restoration.

The walls of the outer container and inner bag; which comprise differentthermoplastic plastics, do not generally become welded together. As aresult of the force exerted during squeezing out of the excess materialthrough the blow mould halves, on the one hand the walls of the innerbag and on the other hand the walls of the outer container are weldedtogether in each case. In addition, adhesion occurs in areas of the baseseam between the walls of the inner bag and the outer container. This isa substantial advantage of the process with regard to fixing the innerbag in the base area. Here, the adhesion is such that when the base seamof the outer container is broken off, one of the two seam sides remainsattached to the seam of the inner bag whilst the other seam side of theouter container does not remain fixed to the inner bag. In this way,axial fixing of the inner container is guaranteed despite this breakingoff, even in embodiments where the seam of the outer container is brokenoff over its entire length Fixing of the inner bag is of specialsignificance in application cases where a canula is inserted into thecontainer and detachment of the inner bag from the base area could leadto damage or blockage of the canula. Damage to the inner bag is excludedin the process according to the invention, since the seam is onlypartially cut off and hence the inner bag is firmly closed even afterimplementation of the cutting process by the remaining inner bag weldseam. In contrast to the process according to the prior art, theconfiguration of the pressure equalisation opening is not produceddirectly by the cutting process but rather by application of the forceand breaking off the seam. The wastage rate is minimised. Variants ofthe process are advantageous wherein an axial force, exertedsubstantially parallel to the longitudinal axis of the container, isbriefly introduced after at least partially breaking off the base seamand before introduction of the radial force so that the base seam atleast partially breaks open.

The axially-introduced force primarily serves to break open the baseseam whilst the effect, or the purpose, of the radially-introduced forcecan be seen as the permanent deformation of the base seam. In spite ofthis, both forces are involved in both the deformation of the container,especially the base area, and the breaking-open process, wherein at onepoint the breaking-open process and at another point the deformationhave precedence.

Processes are preferred which are characterised in that the axial forceis introduced in the form of a blow.

Process variants are favourable wherein the production of the containertakes place without the formation of a shoulder seam in the form of asqueeze seam.

This process is preferably carried out so that when the base seam isbroken off, the material which forms the inner bag remains stuck, on oneside of the base seam, to the outer container and the ends of the baseseam, whereupon an axial fixing is maintained. In this case, thepressure equalisation opening between the inner bag and the outercontainer is disposed on the opposite side of the base seam.

A process is favourable where the base seam of the outer container isonly partially broken off and the seam of the inner bag is fixed by thepart of the base seam of the outer container which is not broken off.

In a preferred process, the base seam is cut off and the force whichopens the outer container and permanently deforms it is exerted in oneworking step. This can be translated as meaning that a cutting tool anda tool for breaking off the seam work together and almost simultaneouslyin one working step. A very effective process variant provides thatcutting off the base scam and application of the force which opens andpermanently deforms the outer container is not only realised in oneworking step but also by one tool, in this case the cutting tool.

It is expedient that the base seam is cut off and the force which opensand permanently deforms the outer container take place in separate,closely-sequential work steps. The size of the container which is to beproduced can be a deciding factor for the one or the other variant.

A process variant is recommended where the action of cutting off thebase seam and application of the force which opens and permanentlydeforms the outer container takes place in the plastic blowing machine,especially when the container is still disposed within the closed blowmould. The container, which is 40 to 70° C. warm during the cuttingprocess, is stabilised in this way. A basic advantage is theminimisation of processing machines and apparatus and the removal ofadditional work steps. In this way, costs are reduced and productivityincreased.

However, in individual cases it can again be expedient if cutting offthe base seam and application of the force which opens and permanentlydeforms the outer container occurs on a machine which is attached to theplastic blowing machine. This also falls within the framework of theinvention.

In most cases it is a process wherein the container is configured to bebottle-shaped and the inner bag is fixed in the area of the bottle neckin addition to being fixed in the area of the base. Here, processeswherein the inner bag is at least partially clamped in the wall of theouter container on formation of the bottle neck are especiallyfavourable. This can easily be realised during the course of theprocess. If the diameter of the pre-moulding in the area of the futurebottle neck is greater than the corresponding diameter of the blowmould, the excess material is squeezed out when the blow mould is closedand a weld seam results on the inner bag or the inner bag is fixed tothe outer container.

The process can be arranged, using the corresponding blow mould, so thatthe bottle neck is configured with a projection protruding outwards inthe radial direction on its face side. This can be necessary if thecontainer is to be provided in a later process with a pump or anatomiser, which is preferably attached to the bottle neck.

In this case, the inner bag can be connected with the outer container bymeans of a part of an upright or horizontal fold, thus attainingadditional fixing.

Process variants are preferred where the projection is exclusivelyformed from material of the outer container.

In correspondence with the described process, at least one pressureequalisation opening is provided in the base area with the containeraccording to the invention, resulting from cutting off, breaking off anddeformation of the base seam, wherein one side of the base seam theinner bag remains adhered to the container and the ends of the baseseam, and is thus axially fixed.

Advantageous embodiments of the container state that the container isbottle-shaped and that the bottle neck has a projection extendingoutwards in the radial direction on its face side which can be necessaryfor the adaptation of a pump of an atomiser. However, the additionalfixing in the area of the bottle neck and its embodiments according toclaims 21 and 23 are a part of the invention. As is the feature whereinthe projection is exclusively formed from material of the outercontainer.

The invention is explained in greater detain in the following text withreference to various drawing figures. The following are shown:

FIG. 1 cross-section in the direction of the container central axisthrough a first embodiment example of the container,

FIG. 2 cross-section in the direction of the container central axisthrough the bottle neck of a second embodiment example of the container,

FIG. 3 cross-section in the direction of the container central axisthrough the base area before the cutting process step,

FIG. 4 cross-section in the direction of the container central axisthrough the base area after the cutting process step,

FIG. 5 elevation of the container base in the direction of the containercentral axis,

FIG. 6 elevation of the container base in the direction of the containercentral axis, after the breaking off and deformation process steps, and

FIG. 7 cross-section in the direction of container central axis throughthe base area after the breaking off and deformation process steps.(detail X from FIG. 1)

In the following text, identical items are referred to by the samereference characters.

FIG. 1 shows a cross-section through an embodiment example of thecontainer 1 in the direction of the container central axis 9. Thecontainer, comprising an outer container 2 and an inner bag 3, isbottle-shaped in the present embodiment example. It has a projection 7on its bottle neck 6 which is disposed on the end of the bottle neck 6where the container opening 8 is located. The base seam 5 is disposed inthe extension of the container central axis 9 in the base area 4 of thecontainer 1, about the pressure equalisation opening 10 which belongsthereto. It is clearly shown that the projection 7 is formed frommaterial of the outer container 2.

FIG. 2 shows a cross-section in the direction of the container centralaxis 9 through the bottle neck 6 of a second embodiment example of thecontainer. The bottle neck 6 has a rectangular projection 7 on its faceside directed towards the container opening 8. In contrast to theembodiment example shown in FIG. 1, the rectangular projection 7 has thespecial feature that it is formed from both the material of the outercontainer 2 and the inner bag 3, so that in addition to its fixing inthe area of the base, the inner bag 3 is especially fixed in the area ofthe bottle neck 6.

FIG. 3 shows a cross-section through the base area 4 and the base seam 5disposed here after the blowing process but before the cutting process.The base seam 5, which results from squashing the excess material withthe help of the two blow mould halves, has the shape of a dragon's tailafter the actual forming process. The inner bag 3 is clamped between thewalls of the outer container 2 in the area of the base seam 5.

FIG. 4 shows a cross-section through the base area 4 and the base seam 5disposed here after carrying out the cutting process in which the baseseam 5 was partially cut off.

FIG. 5 shows an elevation of the base area with a view in the directionof the container central axis 9 after the base seam 5 has been partiallycut off. The structure of the base seam 5 can be clearly seen, which isformed centrally by the walls of the inner bag 3 and is limited on bothsides by the walls of the outer container 2. The radial forces F, whichare exerted into the base area 4 in the direction of the seam to break,open the base seam 5 and deform the outer container 2, are also shown.An axial force, which can optionally be introduced is not shown orprovided in the present embodiment example.

FIG. 6 shows an elevation of the base area 4 with a view in thedirection of the container central axis 9 and the base seam 5 disposedin the base area 4, under the effect of the radial forces F which workin the direction of the seam. It is clearly shown how the containerdeforms and the base seam 5 breaks under the effect of the forces,forming a pressure equalisation opening 10. In this special embodimentexample, on one side of the base seam 5 the inner bag 3 remains stuck tothe outer container 2 and the ends of the base seam 11 and is thusaxially fixed. The pressure equalisation opening 10, which is limited bythe outer container 2 and the inner bag 3, is formed on the oppositeside and can thus compensate for a pressure difference between the innerbag 3 and the outer container 2.

FIG. 7 shows a cross-section in the direction of the container centralaxis 9 through the base area 4 and the base seam 5 disposed therein. Thepressure equalisation opening 10 can clearly be seen between the innerbag 3 and the outer container 2.

Reference Character List

1. Container

2. Outer container

3. Inner bag

4. Base area

5. Base seam

6. Bottle neck

7. Projection

8. Container opening .

9. Container central axis

10. Pressure equalisation opening

11. Ends of the base seam

What is claimed is:
 1. A process for the production of a containerhaving a container opening, the container having substantially rigidouter container having an inner surface and an outer surface and aninner bag having an inner surface and an outer surface disposed therein,the outer container having a pressure equalization opening in a basearea thereof for equalizing a pressure difference between the outercontainer and the inner bag, wherein the outer container and inner bagrespectively comprise different thermoplastic plastics not bonded toeach other, the process comprising: coextruding a preliminary mouldinghaving an inner surface and an outer surface from an inner coaxial tubeand an outer coaxial tube having sufficient length for manufacture ofthe container using a blow mould having interior surface contours, toform an outwardly-projecting base seam in the preliminary moulding andto compress excess material in a base area of the preliminary mouldingsuch that: (i) material of the outer coaxial tube in contact near thebase seam is welded together, (ii) the inner coaxial tube forming theinner bag is clamped, axially fixed, and welded between the wallsections of the outer container, and (iii) the inner bag is subjected topressure so that the outer surface of the preliminary moulding lieagainst the interior contours of the blow mould, wherein on closing theblow mould and with the associated formation of the base seam, the outersurface of the inner bag is at least partially fixed axially by theinner surface of the outer container and at least one pressureequalization opening is formed in that the base seam is at leastpartially cut off after shaping, and a radial force which acts in thedirection of the base seam is exerted in the base area in such a waythat the base seam breaks open, and wherein the temperature of thepreliminary moulding is between 40° C. and 70° C. when the base seam iscut off and the outer container is still plastically deformable to somedegree, so that a permanent deformation results from the force which isnot neutralized by elastic restoration.
 2. The process according toclaim 1, wherein when the base seam is broken open, the, materialcomprising the inner bag remains stuck, on one side of the base seam, tothe outer container and the ends of the base seam, whereby axial fixingis maintained.
 3. The process according to claim 2, wherein the baseseam of the outer container is only partially broken open and the seamof the inner bag is fixed by the unbroken part of the base seam of theouter container.
 4. The process according to claim 3, wherein thecutting off of the base seam and the application of the force whichopens and permanently deforms the outer container occur simultaneouslyin one work step.
 5. The process according to claim 3, wherein thecutting off of the base seam and the application of the force whichopens and permanently deforms the outer container occur separately inseparate work steps.
 6. The process according to claim 3 ,wherein thecutting off the base seam and the application of the force which opensand permanently deforms the outer container occur in the plastic blowingmachine.
 7. The process according to claim 3, wherein the container isconfigured in the shape of a bottle having a bottle neck with a faceside.
 8. The process according to claim7, wherein the inner bag is fixedin the area of the bottle neck in addition to the fixing in the basearea.
 9. The process according to claim 8, wherein the inner bag is atleast partially clamped in the wall of the outer container during theformation of the bottle neck.
 10. The process according to claim 9,wherein the bottle neck is configured with a projection on its face sideextending outwards in the radial direction.
 11. The process according toclaim 10, wherein the inner bag is connected with the outer container bymeans of an upright or horizontal fold in the area of the projection.12. The process according to claim 1, wherein the base seam of the outercontainer is only partially broken open and the seam of the inner bag isfixed by the unbroken part of the base seam of the outer container. 13.The process according to claim 12, wherein the cutting off of the baseseam and the application of the force which opens and permanentlydeforms the outer container occur simultaneously in one work step. 14.The process according to claim 13, wherein the cutting off the base seamand the application of the force which opens and permanently deforms theouter container occur in a machine which is attached to the plasticblowing machine.
 15. The process according to claim 12, wherein thecutting off of the base seam and the application of the force whichopens and permanently deforms the outer container occur separately inseparate work steps.
 16. The process according to claim 12, wherein thecutting off the base seam and the application of the force which opensand permanently deforms the outer container occur in the plastic blowingmachine.
 17. The process according to claim 12, wherein the cutting offthe base seam and the application of the force which opens andpermanently deforms the outer container occur in a machine which isattached to the plastic blowing machine.
 18. The process according toclaim 12, wherein the container is configured in the shape of a bottlehaving a bottle neck with a face side.
 19. The process according toclaim 18, wherein the inner bag is fixed in the area of the bottle neckin addition to the fixing in the base area.
 20. The process according toclaim 19, wherein the inner bag is at least partially clamped in thewall of the outer container during the formation of the bottle neck. 21.The process according to claim 20, wherein the bottle neck is configuredwith a projection on its face side extending outwards in the radialdirection.
 22. The process according to claim 21, wherein the inner bagis connected with the outer container by means of an upright orhorizontal fold in the area of the projection.
 23. The process accordingto claim 1, wherein the cutting off of the base seam and the applicationof the force which opens and permanently deforms the outer containeroccur simultaneously in one work step.
 24. The process according toclaim 23, wherein the cutting off the base seam and the application ofthe force which opens and permanently deforms the outer container occurin the plastic blowing machine.
 25. The process according to claim 1,wherein the cutting off of the base seam and the application of theforce which opens and permanently deforms the outer container occurseparately in separate work steps.
 26. The process according to claim 1,wherein the cutting off the base seam and the application of the forcewhich opens and permanently deforms the outer container occur in theplastic blowing machine.
 27. The process according to claim 1, whereinthe container is within the blow mould.
 28. The process according toclaim 1 , wherein the cutting off the base seam and the application ofthe force which opens and permanently deforms the outer container occurin a machine which is attached to the plastic blowing machine.
 29. Theprocess according to claim 7, wherein the container is configured in theshape of a bottle having a bottle neck with a face side.
 30. The processaccording to claim 29, wherein the inner bag is fixed in the area of thebottle neck in addition to the fixing in the base area.
 31. The processaccording to claim 30, wherein the inner bag is at least partiallyclamped in the wall of the outer container during the formation of thebottle neck.
 32. The process according to claim 31, wherein the bottleneck is configured with a projection on its face side extending outwardsin the radial direction.
 33. The process according to claim 32, whereinthe inner bag is connected with the outer container by means of anupright or horizontal fold in the area of the projection.
 34. Acontainer with a container opening substantially comprising a rigidouter container and an inner bag disposed therein, the container madeaccording to the process of one of claims 1 to 33.